Air-compressor.



H. PARKHURST.

I AIR COMPRESSOR. APPLICATION mp0 NOV.25.19l3.

Patented Oct:17;1916.

2 SHEE T SSHEET l.

H. PARKHURST.

AIR COMPRESSOR. APPLICATION FILED NOV. 25. I9I3- Patented Oct. 17, 1916.

2 SHEETS-SHEET 2.

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nniann snares earner @FFEQE HARLEIGH IPARKHURST, OE WALIOLE, NEW HAMPSHIRE, ASSIGNOR T0 AGNES BURTOT'T, OE MINNEAPOLIS, MINNESOTA.

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To all whom it may concern:

Be it known that I, HARLEIGH PARKHURST, a citizen of the United States, and resident of Walpole, in the county of Cheshire and State of New Hampshire, have invented new anduseful Improvements in Air-Compressors, of which the following is a specification.

This invention relates to air compressors, and particularly portable air compressors, and its object is to provide a novel and improved air compressor of simple and compact construction, capable of great efficiency and high speed.

With this invention the crank-case isutilized. for the compression of air during thestroke of the piston which corresponds to the suction stro (e in ordinary single acting air compressors or pumps, and the air thus compressed is introduced into the cylin- 'derat about the time, or just before, the

air chtnpressor containing my invention Figs. 2, 3, 4, 5 and 6 represent diagram m'atically successive positions of the parts through one cycle of operation of the compressor shown in Fig. 1; Fig. 7 is a sectional view on line 7-7 of Fig. 1; Fig. 8 is a vertical, central section showing a form of check valve appropriate for said compressor; Figs. 9 and 10 are plan views pf the valve members shown in Fig. 8; and Fig. 11 is a section on line 11-11 of Fig.

A represents a cylinder, B a piston working within said cylinder, and (l a crank-case directly connected to one end of the cylinder and forming part of the air passage, through which air passes and 111 which air is 'com Specification of Letters Patent.

pressed, on its way to the discharge or compression end of the cylinder, as hereinafter described. The crank shaft 0 extends [through the crank-case and may be driven by a pulley or any suitable means (not shown). The crank shaft 0 carries the crank c, which reciprocates the piston 13 by link or connecting rod 0 pivoted at one end to the crank vand at the other end to the piston. D represents a sleeve valve fitted to slide within cylinder A between the piston Band the walls of the cylinder. Motion is imparted to sleeve valve D by connecting rod d which is pivoted at one end to a pin or stud (l on the sleeve, and having at the other end a strap a! engaging an eccentric (or crank) which is fast to and actuated by crank shaft 0. The eccentric d and crank c" are angularly arranged with relation to each other, so that the strokes of the piston B and the sleeve valve D, instead of taking place in unison, are differently timed. In the embodiment of the, invention illustrated in the drawings, the eccentric d and crank c are arranged at an angle of about 90?, and the piston 13 is therefore timed to make its stroke a little in advance of .the-

I Patented Get. 1'7, lens. I

Application filed November 25, 1913. Serial No. 803,014.

inlet passage opening from supply port 7,

communicates with the other end of the cylinder to admit air to the cylinder at the main compression side of the piston. The cran k-case outlet passage It connects the crank-case C with the discharge end of end of its crank case compression stroke.

The valveD is provided with ports 2', 7' and 70, which cooperate respectively with passages c, h and a; Said ports are controllcd by the relative movements between thesleeveD, the cylindrical walls Z) of the piston. B, and the cylinder A, as hereinafter described. y

E represents the cylinder head having outcylinder A' at a point just beyond the head v of the piston 13 when the piston is at the Qua let ports m, controlled by outwardly openiug check valves, and p the main discharge port ol: the coin n'cssor.

The relative location and arrangement of the ports in sleeve valve D, the air passages through the cylinder and crank-case, and the cvlindrical walls b of the pistoih can best be diiscrihed end understoodhy following the action oi the parts during one con'iplete cycle in the operation of the compressor. In Fig. 1 the ports-are shown in the positions they occupy at the end of the operative or main coi'hpression stroke of the piston. In this position, consideriiiig the rotation of the crank shaftc to he in a clockwise direction. as viewed in the.d1swings the eccentric (5 will have made about threefourths of a revolution,"and ,the sleeve'valv'e D will he about half Way between its two extreme positions, while the crank 0 will he at its center, and.-

the niston. will he at its extreme position in the con'ipression or discharge direction. The port controlling; the crzmlr-case inlet passage 6 will then be open to passage 0, but about to close upon thenext upviard movement of the sleeve 1 the portj \vih register with the crankcase outlet passage it but be closed by the well. F) of the piston; andathe port iv will be out of register with cylinder inlet passage 5 and therefore closed. When the crank c is turned througl'i thefirst part of its rotationjtothe position suhsteiitially as shown in' Fig. :hthe sleeve 1) Will vhe moved upwarih thereby closing inlet passage 6 to the eranlocase, inaii'iiaining crank-case outletpassagc it closed (theport being covered both the cylinder and pistonfl and'o 'iening cylinder inlet passage 5;. through port 7: to the main compression side of the piston. At the sametinie piston B will have started to move 'doivnvard, compressing the air withinthe crank-case and drawing air inward into the cylinder through ort 1 Fig.8 shows the pos iti.on of the parts when thecranl; c hashcen turned to a position a little. short of the end of the crankcase compression stroke" Both, the sleeve D and piston B will then be moving; don-nward, and port '5 will be approaching oassage e. The piston will, however, have moved in advance of the (lOVVIlVViElLl stroke of the sleeve as to cover port '1: and keep e-closed, allowing the compression of air Within the crank-case to continue. The port K admitting air on the main com.- pression side the piston is about to close, by reason of the downward movement of the sleeve D, and the port 7' is still closed but is about open volume of air admitted to the cr anlocuse when the piston was in the position shown in Fig. 1., is compressed within the crankcase, and the cylindihon the other side of the piston is filled. with air at substantially etinospherlc pressure. /Vhen the c anh c [it this stage the reaches the end of its crank-case COPQPI'BS sio'n stroke, shown in Fig 4, the sleeve will he approximately.half Way on its down ward inovei'nent, and port y' "vvill henncovered. by piston 3 end will register Wltl1- drawnin through the main inlet passage g. i

Asthe crank-0 rotates farther to the position shovvn in Fig. 5,,the sleeve D continues its downward movement cutting, ofi the crank-case outlet passage in, and the piston l starts to move upward; and to compress and force the air joutvvard through outlet valve ports m and main discharge port p the continued downward movement of sleeve D maintaining the main cylinder inlet passage g closed As the pressure within the crank-case will already be some-- What above the-atmosphere, it is not necesv sary that the crank-case inlet passage e should open once, as the air will expand sufiiiciently during the first part of the up- \vmtl stroke Without further supply, and at the same time assist-said. stroke. 'In the po- 'sition shown in Fig. 5 the port 6 is about to he uncovered hy the operative or upward stroke of the piston. When crank 0 has made about one-sixth or one-fifth of lts .up-

ward movement the piston B Will uncover ,port i and open inlet passage 6 to admit air to the cranlocase through port i; and both ports j and ii Wlll remain closed, While port 2' will rema n open, as shown in Fig. 6; until the piston hpproaches the end of its main compression stroke. At the completion of the rotation of crank 0 the parts will he' brought into the position shown in Fig. 1 from which we started, and the cycle Will be complete.

It will he understood that the cycle above described cooldhe effected by other means than; the sleeve valve above described, and the invention in its broadest aspects is not limited to that particular form of control valve.

al ith \the above described apparatus it 1 will be seen that, during thecranlocase compression stroke of the piston, air Will be ad'- mitted et atmospheric pressure at the dis charge side of thefipiston, the crank-case in let passage 6 Will he closed, and. the air previously admitted the crank-case at the opposite side oftne piston will be compressed, while the outlet passage from the crank case to the cylinder Will remain closed; that at or about the end of the crank-case compression stroke the main cyliader inlet passage 9 at the discharge side of the piston will close, and the outlet passage 72 from the crank-case to the cylinder will opci permitting the compresse airto enter the cylinder; and that during the first part of the main compression stroke of the piston said passage it will close, passage g will remain closed, and the passage 0 will open to supply air'to the'crank-case, ready for the next crank-case compression stroke. By thus supplementing the supply of air normally drawn into the cylinder on the main compression side of the piston, with additional air forced into the cylinder under the crank-case compression, a higher volu-.

metric efliciency is insured than has heretofore been attainable.

The crank-case is air tight. and forms in effect an auxiliary compression chamber by which the volumetric elliciency of the main compression chamber in the cylinder is augmented by the air supplied from the auxiliary compression chamber through the connecting passage h.

formed in the inner walls of the casing A.

Referring now to' the check valve illustrated in Figs. 7 to 10, the valve ports 11/ are arranged in two concentric circles III the cylinder head E. The outer row of ports is controlled by the annular valve 9 which covers the entire row, and the inner row of ports is controlled by a similar, but smaller 45 annular valve r. The cylinder head E is provided with an annular flange or rim t, which centers and guides the valve ring (1, and a central stud or shaft t which centers and guides the inner ring 7'. Two concentric coil springs, s and a press yalves q and s", respectively, toward their seats. Said springs hear at their upper ends against a disk or frame 0, whi-chis adjustably mounted on shaft 25. By adjusting the screw n which is threaded through the outer wall E of the cylinder head, and bears against disk 0 on the side opposite the springs a and' a, the tension of said springs may be varied uhiformly and simultaneously.

The valve (1 is provided with a series of apertures located at the inner side/ofthe' valve ports m, and consisting, as herein shown, of recesses (1' formed in the inner periphery of the valve when the valve is lifted. When the valveis lifted from its seat by the compressed air, the 'escape ofair of air wholly past the outer periphery, is

prevented. The inner valve r is similarly provided with a row ofaperturesrf which are arranged at the inner side of the ports m controlled by said valve, for the same pur pose as the apertures q, The use ottwo or: more such annular ,valvcs increases the area of the escape passage, and decreases the valve lit't, thereby stillfurther qnickening'the action of the valves and reducing their tendcncy to pound.

I claim:

1. An air compressor comprising'acylinder constituting a mainco npression chal her, a piston working in s'aid cylinder, 21

air tight auxiliary compression chamber op the end oi. said piston opposite the main compression chamber, inlet passages for said chambers, a connecting passage between said main and auxiliary compression chambers, and means to control said passages whereby the air 'adiilittecl to the main compression chamber through its inlet passage during the a1ix1hary"compress1on stroke ofthe piston.will be supplemented in volume by air compressed Within the auxiliary compressionchamber, which air is admitted to-the main compression chamber through said connecting passage.

2. An air compressor comprising a cylinder, a piston working therein, a crank to' 'reciproc'atesaid piston, an air tight crankcase connected. to said cylinder forming part of an air passage to the cylinder, 9, main air inlet passage communlcatlng with the, cyl- 1nder, an air inlet passage communicating with the crank-case, a crank-case outlet passage connecting the crank-caseand the cylinder, and means controlling said passages,

adapted to open said main inlet passage to.

the cylinder during the crank-case compressionstroke of the piston, also to admit air tp the crank-ease during the main compression stroke of the piston, also to close said main cylinder inlet passage substantially throughout the main compression stroke .of the piston, also to close the crank-case inlet passage substantially throughout the crankcase compression stroke of the piston, Where:

by the piston will comp'ressthe air in the c ank-case, also to maintain said crankcase outlet passage closed dur ng both the main compression stroke and the crankcase com pression stroke excepting at about the time of the reversal. of the piston from the crank-= case compression stroke to the rosin compression stroke and momenserily to open said crank-case outiet'pessoge at about said. time 5 of reversal of the piston, thereby admitting air compressed in the crank-case to the cylinder.

3. An air compressor comprising a cylinder, a piston working therein, a. crank to 10 reciprocate said piston, an air tight crank- "ese connected to said cylinder forming part of an air passage he the cylinder, e main sir iniet'passage communicating with he cylinder, an air inlet passage coimmuiiceting with-the crankcase, a crank-case outlet pessage connecting the crank-case and the cylinder, and a sleeve valve controlling said passages and fitted to slide in said cylinder between said piston and the walls of the cyl- -inder, adopted toopen said main inlet passage to the cylinder during the crank-case compression stroke of the piston, also to sch mil; air to the crankcase during the .main

compression stroke of the piston, also so close said main cylinder inlet passage substantially throughout the main compression stroke of the piston, also to close she crankcase inlet passage substantialiy throughout the crank-case compression stroke of-tho api-ston, whereby the, piston will compress the air in the crankcase, also to maintain said crank-case outlet passage closed during both the main compression stroke and the crank-case compression sfiroke excepting e about the time of the reversal of the piston from the crank-case compression stroke to she main compression stroke, and momeniorily to open said crsnlt-oese ouilet passage at about said iimeof reversal oi she I piston, thereby scimiitiiig ailfGOlflPlGSS d in the crank-case so the cylinder.

4. An air compressor, comprising cylinder, a piston Working iaherein, a crank shaft and creek to reciprocate said pision on air tight crook-case connected to cylinder forming m of on air passage she cylinder, e sleeve vaive fitted to slide iii said cylinder between the piston and walls of the cylinder and actuated. by crank-shaft, a main air inlet passage to said cylincier it the main cmnpression'end the piston, anair inlet passage to the craniacase, and on air outlet passage from the crank-case to the cylinder said sleeve velvehmdng ports cooperating; with. said several passages and conirolleai by the cylinder and piston to open said main inlet passage to ihe cylinder during the crankcase compression stroke of the piston and to close the same during the main compression stroke of the piston, to close said air inlet passage to the crank-case during siliol crank-case COHIPI'Q"- sion stroke and to open the some (luring the main compression stroke, onci to close said air outiei passage from the crank-case to the cylinder during both strokes and. open she se ne m'onientm'ily at about the time of the reversal of the piston from the crsni-z-case compression stroke to the main compression stroke.

Signed at Boston, Mr issechusetts, this Qlsafi (layof November, 1913.

' HiiRLEiGH HUEST Witnesses:

ROBERT C'osirMeii',

CHARLES D, Whose-Emir. 

